Rlp router

ABSTRACT

A practical inter-carrier roaming solution by way of a roaming location protocol (RLP) router that provides consistent location support across heterogeneous wireless network standards. The RLP router maintains connectivity to each location server in a roaming ecosystem, alleviating the need for an expensive and impractical mesh network of location servers. When a home location server (H-LS) determines it cannot locate a subscriber device because the subscriber device is roaming, the H-LS sends an RLP request to the RLP router. The RLP router then routes the RLP request to a serving location server (S-LS), which subsequently returns location information for the roaming subscriber device. The RLP router maintains mobile switching center ID (MSCID) to location based services (LBS) mappings for routing RLP requests. The RLP router may also maintain rough MSC-level positioning data for each MSCID to enable the RLP router to resolve certain location fixes without utilizing an S-LS.

This application is a continuation of U.S. patent application Ser. No.13/922815, filed 20 Jun. 2013; which is a continuation-in-part of U.S.patent application Ser. No. 13/348836, filed 12 Jan. 2012; which is acontinuation-in-part of U.S. patent application Ser. No. 13/374104,filed on 12 Dec. 2011; which claims priority from U.S. Provisional No.61/457138, filed 12 Jan. 2011 and from 61 /457029, filed 13 Dec. 2010.The present invention also claims priority from U.S. Provisional No. 61/664388, filed 26 Jun. 2012, the entirety of all of which are expresslyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to wireless telecommunication. Moreparticularly, it relates to location roaming in CDMA, GSM, IMS/LTE,SUPL, etc. environments.

2. Background of the Related Art

Conventional wireless devices typically contain multiple cellular radiosto support roaming onto different networks, e.g., Code Division MultipleAccess (CDMA) networks, Global System for Mobile Communications (GSM)networks, Long Term Evolution (LTE)/IP Multimedia Systems (IMS)networks, Wi-Fi, Secure User Plane Location (SUPL), etc. A wirelessdevice is roaming when operating on a network other than the device'shome/direct network.

Conventional 3^(rd) Generation Partnership Project (3GPP) standards usea Roaming Location Protocol (RLP), developed by an Open Mobile Alliance(OMA) standards body, to support location determination of roamingsubscriber devices. A Roaming Location Protocol (RLP) is aninter-location server protocol over which location servers exchangepositioning data for devices roaming on a visited network.

FIG. 4 depicts a conventional implementation of the Roaming LocationProtocol (RLP).

As portrayed in FIG. 4, a home location server (H-LS) 400 and a servinglocation server (S-LS) 420 (i.e. a location server currently serving aroaming subscriber device) exchange positioning data for a roamingsubscriber device via Roaming Location Protocol (RLP) 410 messages.

Location servers supported within the Roaming Location Protocol (RLP)include Gateway Mobile Location Centers (GMLC) (i.e. GSM locationservers) SUPL Location Platforms (SLP) (i.e. SUPL location servers), andMobile Positioning Centers (MPC) (i.e. CDMA location servers).

The 3^(rd) Generation Partnership Project (3GPP) specifically adoptedthe Roaming Location Protocol (RLP) to provide roaming location supportwithin Secure User Plane Location (SUPL) and Global System for MobileCommunications (GSM) technologies. The Roaming Location Protocol (RLP)also provides roaming location support for Code Division Multiple Access(CDMA) technologies (CDMA support is introduced in RLP 1.1). However,CDMA standards do not yet support the Roaming Location Protocol (RLP).

Unfortunately, several issues arise when attempting to use the RoamingLocation Protocol (RLP) as specified within 3GPP standards and asproposed for CDMA. For instance, conventional implementations of theRoaming Location Protocol (RLP) do not provide location heterogeneity.In particular, the Roaming Location Protocol (RLP) does not directlysupport location determination for subscriber devices roaming on avisited carrier network (i.e. any carrier network that differs from adevice's home/direct carrier network). Hence, positioning data is notobtainable for, e.g., a U.S. CDMA carrier device roaming on a EuropeanGSM network.

Moreover, the Roaming Location Protocol (RLP) relies on a mesh networkof interconnected location servers.

FIG. 5 depicts an exemplary mesh network of location servers.

As depicted in FIG. 5, conventional 3GPP standards require a locationserver to know about and maintain connectivity to all other locationservers in a roaming ecosystem. This requirement results in an expensiveand impractical mesh network 510 of location servers 500 a-500 f. A meshnetwork 510 of location servers 500 a-500 f increases a networkcarrier's vulnerabilities, as it introduces multiple ingress/egresspoints in to a network. Multiple ingress/egress points in a network alsopresents cost and risk issues, since each ingress/egress point must bemaintained, monitored, and controlled.

The Roaming Location Protocol (RLP), as defined for GSM and SUPL,requires an expensive mesh network 510 of location servers 500 a-500 fand is therefore typically not adopted in practice. When the RoamingLocation Protocol (RLP) is implemented, the solution is costprohibitive.

An SS7 mechanism is defined for roaming location support within the CDMAcontrol-plane. However, this SS7 mechanism is cost-prohibitive andtherefore not adopted in practice.

Moreover, a proprietary solution is defined for roaming location supportwithin the CDMA user-plane. However, this solution unfavorably requirescarriers to share network descriptions with other carriers, and istherefore not adopted in practice.

Additional solutions do exist for user-plane roaming. However, adoptionof these standards is lacking due in part to: partial carrier supportfor the user-plane, low SUPL V2.0 adoption (within which user-planeroaming is defined), undesirability of Base Station Almanac data sharing(a requirement in conventional user-plane roaming standards), anddifficulty justifying a return on investment (ROI).

Additional solutions also exist for control-plane roaming. However,adoption of these standards is lacking due in part to: a lack ofinter-carrier agreements, a low adoption of IS-881 roaming features(which define several location request signaling messages), a costprohibitive LPREQ feature (an IS-41 message used to query a homelocation register (HLR) for the address of a serving location server(S-LS)), interoperability issues resulting from dissimilar vendorimplementations, prohibitive costs of features, maintenance mappings,translations, etc., and difficulty justifying a return on investment(ROI).

Conventional roaming solutions do not provide consistent locationsupport for CDMA networks, nor do they provide consistent locationsupport across heterogeneous network standards.

Standard roaming solutions also fail to identify the cost disparitybetween coarse location and precise location fixes. A coarse locationfix (typically resolved by a location server) is a relativelyinexpensive activity that does not significantly tax a servinginfrastructure. Alternatively, a precise location fix is expensive to aserving infrastructure, since session license costs are high.Infrastructure utilization is also considerably higher for a preciselocation fix, since interaction for a precise location fix stretches allthe way to a target device. Failure to account for the cost disparitybetween coarse and precise location fixes is another factor preventingadoption of conventional location roaming solutions.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become apparent tothose skilled in the art from the following description with referenceto the drawings, in which:

FIG. 1 shows an exemplary RLP router, in accordance with the principlesof the present invention.

FIG. 2 shows an exemplary process flow for obtaining a coarse locationfix for a roaming subscriber device using an RLP router, in accordancewith the principles of the present invention.

FIG. 3 shows another embodiment of an exemplary process flow for usingan RLP router to obtain a coarse location fix for a roaming subscriberdevice, in accordance with the principles of the present invention.

FIG. 4 depicts a conventional implementation of the Roaming LocationProtocol (RLP).

FIG. 5 depicts a conventional mesh network of location servers.

SUMMARY OF THE INVENTION

A practical inter-carrier roaming solution for providing consistentlocation support across heterogeneous network standards (e.g. GlobalSystem for Mobile Communications (GSM), Secure User Plane Location(SUPL), Code Division Multiple Access (CDMA), Long Term Evolution(LTE)/IP Multimedia Subsystem (IMS), etc.), comprises a Roaming LocationProtocol (RLP) router. The inventive RLP router maintains connectivityto each location server in a roaming ecosystem, thereby alleviating theneed for an expensive and impractical mesh network of location servers.In accordance with the principles of the present invention, a homelocation server (H-LS) need only maintain connectivity to an RLP routerto obtain consistent roaming location support.

In accordance with the principles of the present invention, when a homelocation server (H-LS) (e.g. GMLC, MPC, SLP, etc.) determines that itcannot obtain location information for a target subscriber devicebecause that target subscriber device is roaming, the home locationserver (H-LS) sends an RLP request for location information to the RLProuter 100. The RLP router then routes the RLP request to an appropriateserving location server (S-LS) (i.e. a location server currently servingthe target subscriber device). The serving location server (S-LS)subsequently responds to the RLP request with location information forthe roaming subscriber device and the RLP router routes locationinformation back to the requesting home location server (H-LS).

The RLP router resides outside of any carrier network. In accordancewith the principles of the present invention, the RLP router maintainsmobile switching center ID (MSCID) to location based services (LBS)mappings, to route RLP requests. In a particular embodiment, the RLProuter may also maintain rough, MSC-level positioning data for eachMSCID stored thereon.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention provides a practical inter-carrier roamingsolution by way of an inventive Roaming Location Protocol (RLP) router.The inventive inter-carrier roaming solution provides consistentlocation support across heterogeneous network standards, e.g., GlobalSystem for Mobile Communications (GSM), Secure User Plane Location(SUPL), Code Division Multiple Access (CDMA), Long Term Evolution(LTE)/IP Multimedia Subsystem (IMS), etc.

Conventional user-plane and control-plane roaming solutions are costprohibitive and typically not adopted in practice.

Conventional 3^(rd) Generation Partnership Project (3GPP) standards usea Roaming Location Protocol (RLP) to support location determination ofroaming subscriber devices. Unfortunately, conventional implementationsof the Roaming Location Protocol (RLP) rely on an expensive andimpractical mesh network of location servers and do not provide locationsupport across heterogeneous network standards.

The inventive RLP router alleviates prohibitive costs associated withconventional control-plane and user-plane roaming solutions andovercomes implementation shortcomings associated with conventional 3GPPRLP usage.

FIG. 1 shows an exemplary RLP router, in accordance with the principlesof the present invention.

As portrayed in FIG. 1, an RLP router 100 maintains connectivity to eachlocation server 110 a-110 h in a roaming ecosystem. In accordance withthe principles of the present invention, a home location server (H-LS)queries an RLP router, as opposed to a serving location server (S-LS),to request location information for a roaming subscriber device. Thissolution alleviates the need for a home location server (H-LS) to knowabout and maintain connectivity to every other location server inexistence.

The disclosed embodiments of an RLP router 100 reside outside anycarrier's network. In accordance with the principles of the presentinvention, when a home location server (H-LS) (e.g. a gateway mobilelocation center (GMLC), a mobile positioning center (MPC), a SUPLlocation platform (SLP), etc.) determines that location information fora target subscriber device is unobtainable because the target subscriberdevice is roaming, the home location server (H-LS) sends an RLP requestfor location information to the RLP router 100. The RLP router 100 thenroutes the RLP request to an appropriate serving location server (S-LS)(i.e. a location server currently serving the target subscriber device).The serving location server (S-LS) subsequently responds to the RLPrequest with location information for the roaming subscriber device, andthe RLP router routes location information back to the home locationserver (H-LS).

In accordance with the principles of the present invention, a homelocation server (H-LS) need only maintain connectivity to an RLP router100 to achieve consistent location roaming support. Thus, the presentinvention alleviates the need for a mesh network of location servers (aspreviously depicted in FIG. 5).

FIG. 2 shows an exemplary process flow for obtaining a coarse locationfix for a roaming subscriber device using an RLP router, in accordancewith the principles of the present invention.

As portrayed in step 10 of FIG. 2, a location service client (LCS) 200sends a mobile location protocol (MLP) standard location immediaterequest (SLIR) message to a home location server (H-LS) (e.g. an MPC,GMLC, SLP, etc.) 212, requesting location information for a targetsubscriber device.

As depicted in step 12, the home location server (H-LS) 212 sends ashort message service request (SMSREQ) message to a home locationregister (HLR) 210 to request location information for the targetsubscriber device.

In step 14, the home location register (HLR) 210 returns an SMSREQresult message to the home location server (H-LS) 212, with the address(i.e. an MSCID) of a mobile switching center (MSC) currently serving thetarget subscriber device (i.e. a serving mobile switching center(S-MSC)) 216.

In step 16, the home location server (H-LS) 212 receives the MSCID ofthe serving mobile switching center (S-MSC) 216 and determines that theserving mobile switching center (S-MSC) 216 is not a home mobileswitching center (H-MSC) (i.e. the target subscriber device is roaming).

As depicted in step 18, the home location server (H-LS) 212 then sends aroaming location protocol (RLP) standard roaming location immediaterequest (SRLIR) message to the inventive RLP router 100, containing theMSCID of the serving mobile switching center (S-MSC) 216 and a mobiledirectory number (MDN) for the target subscriber device.

In step 20, the RLP router 100 maps the MSCID received thereon, to aserving location server (S-LS) (i.e. a location server currently servingthe target subscriber device) (e.g. an MPC, GMLC, SLP, etc.) 214.

As depicted in step 22, the RLP router 100 forwards the RLP SRLIRmessage received thereon to the serving location server (S-LS) 214(identified in step 20).

In step 24, the serving location server (S-LS) 214 receives the RLPSRLIR message and transmits an intersystem position request (ISPOSREQ)message to the serving mobile switching center (S-MSC) 216, with themobile directory number (MDN) of the target subscriber device.

In step 26, the serving mobile switching center (S-MSC) 216 returns anintersystem position request (ISPOSREQ) result message to the servinglocation server (S-LS) 214, comprising a cell ID of a base stationcurrently serving the target subscriber device.

In step 28, the serving location server (S-LS) 214 returns a roaminglocation protocol (RLP) standard roaming location immediate answer(SRLIA) message to the inventive RLP router 100, with positioning datafor the cell ID of the base station currently serving the targetsubscriber device.

As depicted in step 30, the RLP router 100 then forwards the RLP SRLIAmessage received thereon to the home location server (H-LS) 212.

In step 32, the home location server (H-LS) 212 returns a mobilelocation protocol (MLP) standard location immediate answer (SLIA)message to the requesting location service (LCS) client 200, containingpositioning data for the cell ID of the base station currently servingthe target subscriber device.

Note that FIG. 2 depicts exemplary flows/scenarios supported by theinventive RLP router 100, and not a complete set of flows/scenarios.

FIG. 3 shows another embodiment of an exemplary process flow for usingan RLP router to obtain a coarse location fix for a roaming subscriberdevice, in accordance with the principles of the present invention.

As portrayed in step 40 of FIG. 3, a location service client (LCS) 200sends a mobile location protocol (MLP) standard location immediaterequest (SLIR) message to a home location server (H-LS) (e.g. an MPC,GMLC, SLP, etc.) 212, requesting location information for a targetsubscriber device.

As depicted in step 42, the home location server (H-LS) 212 sends ashort message service request (SMSREQ) message to a home locationregister (HLR) 210, requesting location information for the targetsubscriber device.

In step 44, the home location register (HLR) 210 returns an SMSREQresult message to the home location server (H-LS) 212, with the address(i.e. an MSCID) of a mobile switching center (MSC) currently serving thetarget subscriber device (i.e. a serving mobile switching center(S-MSC)) 216.

In step 46, the home location server (H-LS) 212 receives the MSCID ofthe serving mobile switching center (S-MSC) 216 and determines that theserving mobile switching center (S-MSC) 216 is not a home mobileswitching center (H-MSC) (i.e. the target subscriber device is roaming).

As depicted in step 48, the home location server (H-LS) 212 sends aroaming location protocol (RLP) standard roaming location immediaterequest (SRLIR) message to the inventive RLP router 100, containing theMSCID of the serving mobile switching center (S-MSC) 216 and a mobiledirectory number (MDN) for the target subscriber device.

In step 50, the RLP router 100 maps the MSCID received thereon, to aserving location server (S-LS) (i.e. a location server currently servingthe target subscriber device), e.g., an MPC, GMLC, SLP, etc.

As depicted in step 52, the RLP router 100 transmits an intersystemposition request (ISPOSREQ) message to the serving mobile switchingcenter (S-MSC) 216, containing an international mobile subscriberidentity (IMSI) for the target subscriber device.

In step 54, the serving mobile switching center (S-MSC) 216 returns anintersystem position request (ISPOSREQ) result message to the RLP router100, with the cell ID of a base station currently serving the targetsubscriber device.

In step 56, the RLP router 100 returns a standard roaming locationimmediate answer (SRLIA) message to the home location server (H-LS) 212,with positioning data for the cell ID of the base station currentlyserving the target subscriber device.

As depicted in step 58, the home location server (H-LS) 212 then returnsa mobile location protocol (MLP) standard location immediate answer(SLIA) message to the requesting location service (LCS) client 200,containing positioning data for the cell ID of the base stationcurrently serving the target subscriber device.

An RLP router 100 may also maintain extremely rough locationdescriptions for various carrier networks. For rough location support,precise location generally refers to GPS positioning. Coarse locationgenerally refers to cell-site sector (and its derivatives) positioning,and rough location, in accordance with the principles of the presentinvention, is a term introduced to represent positioning at the MSCfoot-print level (or even broader). The disclosed RLP router 100contains a mapping of MSCIDs to affiliated location based services(LBS). In a particular embodiment, the RLP router 100 may also maintaina rough position of each MSC's footprint.

In accordance with the principles of the present invention, the RLProuter 100 uses rough location descriptions to return extremely roughlocation information to a home location server (H-LS) 212 when, e.g., aserving location server (S-LS) 214 is unknown, or, e.g., when onlyextremely rough location information is requested.

For instance, an RLP router 100 may return a rough MSC level position toa home location server (H-LS) 212 when RLP quality of service (QoS)requirements (for LCS support) indicate a rough accuracy locationrequest.

Moreover, an RLP router 100 may provide rough, MSC level locationinformation to a home location server (H-LS) 212 when an accuracy policyfor a serving wireless carrier only allows MSC rough accuracy, and/orwhen a throttling policy for a serving wireless carrier would otherwisecause a location request to be rejected.

Additionally, an RLP router 100 may return rough, MSC level locationinformation to a home location server (H-LS) 212 when a serving locationserver (S-LS) 214 fails a location request and does not return afallback MSC rough position result to the RLP router 100 (some MSCsprovide a fallback MSC rough position result and some do not).

By maintaining rough location data, the RLP router 100 is able toresolve certain location fixes without utilizing a serving locationserver (S-LS) 214.

The RLP router 100 is intended to provide global roaming locationsupport. The disclosed RLP router 100 contains CDMA MSC rough locationinformation for those carriers subscribed to the inventive inter-carrierroaming solution. In accordance with the principles of the presentinvention, an RLP router database is populated with reliable andaccurate global CDMA, GSM, SUPL, and IMS/LTE data. The disclosedinter-carrier roaming solution enables at least rough location supportfor all subscribers, wherever voice roaming agreements are in place.

The disclosed RLP router 100 has general benefits. For instance, whenwireless carriers implement an inter-carrier roaming solution by way ofan RLP router 100, wireless carriers are not required to agree on an alluser-plane or all control-plane implementation. Moreover, the RLP router100 alleviates the need for special MSC features and additionalcontrol-plane signaling system number 7 (SS7) connectivity. The spokeand hub design of the inventive roaming solution reduces the cost ofnetwork connectivity for a wireless carrier. Further, the inventiveroaming solution does not require wireless carriers to sharecell-databases.

Use of an RLP router alleviates the need for a home location server(H-LS) to maintain a mapping of MSCIDs to serving location servers(S-LS). Instead, all mappings are performed in the RLP router. Hence,the inventive roaming solution resolves cost and risk issues associatedwith a mesh network of location servers.

The disclosed RLP router can also enforce requestor authentication,authorization, and throttling policies to protect a serving wirelesscarrier. Moreover, the RLP router can enforce a serving carrierposition-accuracy policy, and may also support 4G/LTE Roaming LocationProtocol (RLP) (reducing network complexity, etc.)

The RLP router respects privacy policies defined for each home networkcarrier and is not a location aggregator play. In accordance with theprinciples of the present invention, the RLP router preferably disallowsa wireless carrier to locate subscribers of another wireless carrier.

The disclosed RLP router maintains only MSCID to location based services(LBS) mappings used to route RLP requests. In a particular embodiment,the RLP router may also maintain rough MSC-level positioning data.

The inventive RLP router is a cost effective, low barrier to entrysolution to the conventional difficulties of location roaming. Thedisclosed RLP router is capable of routing between heterogeneousnetworks, and can resolve extremely rough location fix requests.

The disclosed embodiments of the RLP router focus on coarse and roughlocation. Technical obstacles concerning the RLP router are based on agiven carrier's desire for unilateral precise location.

The present invention has particular applicability to cellular carriersthat utilize or provide location roaming. For instance, a group ofcarriers may form a roaming partnership.

While the invention has been described with reference to the exemplaryembodiments thereof, those skilled in the art will be able to makevarious modifications to the described embodiments of the inventionwithout departing from the true spirit and scope of the invention.

What is claimed is:
 1. A method of implementing an inter-carrier roamingsolution for providing consistent location support across heterogeneousnetwork standards including a Long Term Evolution (LTE) networkstandard, comprising: receiving a location request for a roamingsubscriber device at a home location server (H-LS); sending a roaminglocation protocol (RLP) request with a mobile switching centeridentification (MSCID) of a serving mobile switching center (SMSC) to aroaming location protocol (RLP) router; mapping said MSCID received insaid RLP request to an affiliated serving location server (S-LS);sending, from said RLP router, an intersystem position request to saidserving location server (S-LS) in response to said mapping; receiving,at said RLP router, location information for said roaming subscriberdevice from said serving location server (S-LS); and returning, by saidRLP router, said location information received for said roamingsubscriber device to said home location server (H-LS).